Applicability of Social Weight Theory to Brain Computer Interfaces

Applicability Of Social Weight Theory To Brain Computer Interfaces

K. FELIX NAVARRO1

E. LAWRENCE2

D. MARTIN3

1, 2 Faculty of Information Technology, University of Technology Sydney, Sydney, Australia

3 Faculty of Science, University of Technology Sydney, Sydney, Australia

Abstract:The multidisciplinary nature of Brain Computer Interfaces (BCIs) technologies demands scientists and researchers in the area to develop a homogeneous framework and classification of the existent BCI technologies in order to identify, facilitate and accelerate the natural incorporation of the state-of-the-art techniques from the different areas of knowledge. The researchers firstly discuss an extensive literature review and classification of BCI technologies based on Wolpaw’s architecture. As the number of disabled people grows it is vital that researchers develop devices that assist in making the everyday life of such people more bearable. However when developing technologically advanced human computer interfaces researchers have often ignored the importance of the look and feel of the device. In this paper the researchers assess the importance of the Theory of Social Weight when considering BCIs.

Key words: Brain Computer Interfaces, Social weight, health

1 Introduction

Millions of dollars are spent by the government of different nations trying to reincorporate into the society thousands of people with severe disabilities. The following figures from the United States illustrate the magnitude of the problem. There are approximately 200000 cases of spinal cord injuries – growing at a rate of 11000 new cases per year. Of these new cases 56% are in the 16 – 30 age group and the recovery rate is 0.7%[1]. Our research concerns the use of Brain Computer Interfaces as devices to bring an alterative channel of control and communication between people severely disabled and the “outside” world.BCIs are intended to enable both the severely motor disabled as well as the healthy people to operate electrical devices and applications through conscious mental activity [2].

Brain Computer Interface research is multidisciplinary involving scientists, computer professionals, communication specialists and usability experts among others. However, much more work is required on the effect of human factors on usability [3]. A BF++ framework for the implementation of a wide range of Cognitive Biofeedback Systems (CBF) has been developed by [4]. This BF++ system has been described as the most efficient, the most portable across different platforms, the most generic and the one that allows the realization of the cheapest final systems for BCIs in particular. As BCIs become more viable options for users to interact with the physical world it is timely to consider the social aspects behind the design of these devices.

The authors of this paper discuss the applicability of the Theory of Social Weight [5] to Brain Computer interfaces for studying the effects of human factors on BCIs. The Social Weight of an item of technology is defined to be the measure of the degradation of social interaction that occurs between the user and other people caused by the use of that item of technology [5]. It is important to understand that the nature of a BCI is to adapt to humans instead of following the traditional method of forcing human beings to adapt to the computer interface. Social weight is an important concept as humans are inherently social beings. [5]

The structure of the paper is organized in three main sections. The first section outlines the problem formulation and is followed by the architecture of a BCI according to Wolpaw [6]. It provides an overview of the different methods used to improve the functionality of a BCI after the first BCI was created twenty eight (28) years ago by Jacques J. Vidal et al in 1973 [7]. The nextsection outlines the Theory of Social Weight, its significance in wearable computing and discusses its applicability to BCI research. The last section gives our conclusions as well as pointing the way to further research

2Problem Formulation

We have been involved in devising two frameworks as a result of extensive literature reviews of the work already done on Brain Computer Interfaces research[8] with the objective of performing, on the next stage of the study, an evaluation of the suitability of a BCI as a wearable computing networked device. The initial framework was based on Wolpaw’s architecture [6] but further work was undertaken in collaboration with Neil Squire Institute in Canada on the classification and categorization of BCI technologies under the framework proposed by Mason and Birch in [9]. The categorization of the BCI work in this paper is exclusive to Wolpaw’s proposed architecture [6] but a comparison of the problems encountered when classifying the various BCI systems under the two different architectures is currently being analyzed and will form the subject of a future paper.

3BCI Architecture

Before considering the applicability of Social Weight Theory to Brain Computer Interfaces it is necessary to provide an overview of the architecture of a BCI system. It is explained and identified in accordance to the different BCI system phases set out below:

1. Signal Production
2. Signal Processing Component
3. Rendering Component

Table 1 shows the linkages among these 3 phases of the BCI and the interaction with computers.

Phases of the BCI / Explanation / Link with Computer Processes
Signal Production / Electrophysiological activity produced by the user / N/A
Signal Processing Component / Acquisition, amplification, digitalization, filtering and feature extraction of the signal / Filtering of the signal (or Preprocessing, e.g. Artifact Removal),
Categorization (Feature Extraction)
Rendering Component / Translation of the signals to actions and/or commands. E.g. Computer Screen, switching off a device. / Translating Process

Table 1: BCI Phases

The Signal Production is the electrophysiological activity produced by the user. The Signal Processing Component involves the acquisition, amplification, digitalization, filtering and feature extraction of the signal. Therendering component includes the translation of the signals to actions and/or commands.

The official architecture of a BCI is still under discussion, but according to Wolpaw et al. [6] a working BCI is composed of the following parts:

1. Signal Acquisition
2. Signal Processing:
3. Preprocessing or Artifact removal (Includes the cancellation of unwanted data, or noise, as EOG (Electro Oculoogram) and EMG (Electromyographic).
4. Feature Extraction
5. Translation Algorithm
6. Output Device and Output
7. An Operating Protocol

Figure 1: Procedural Architecture of a BCI

3.1 BCI Classification

As described above, there are many characteristics that differentiate one BCI from another. Some of these characteristics can sometimes play a crucial role in the choice of one BCI system over others. This will depend on the type of application or problem that requires solving.

One important BCI project is “The Thought Translation Device” (TTD) by Birbaumer in 1999 [10], which was created to help as a communication device to severely handicapped people by choosing letters on a screen. This device was tested with totally paralyzed, artificially respirated and artificially fed patients, achieving 80-95% success. The individuals needed to be trained for several weeks and months to self-regulate their slow cortical potentials, as means of communication with the TTD [10].

In 1988 the character recognition BCI system by Farwell and Donchin from the University of Illinois was an important BCI application breakthrough [11]. A short review of this project is presented below. A mental prosthesis is used for assessing the speed of a P300-based BCI [11]. This system uses P3 evoked potential (one type pf EEG signal) to write a word in a computer. The P3 component of the evoked potential is a response that occurs 300-450ms after a task-relevant stimulus. Since the P3 component is an inherent response, it requires little training for a subject to use a brain-computer interface (BCI) with this component as the control signal [3].To select the letters, the user has to count the number of times that a row or column containing the letter flashes (at 10 Hz). The system differentiates the letter from the response amplitude from that row and column that is reliably larger from the rest. (2.3 characters/min) (Accuracy 95%).

Figure 2: Display used in the Mental Prosthesis [12].

From the few projects involving invasive techniques, one the most sound ones for its innovative and effective use of epidural electrodes is called “The Brain Response Interface” created by Sutter in 1992 from the Wadsworth Center in USA. The Brain Response Interface [13] requires the implant of epidural electrodes in the user’s brain. The interface utilizes visual evoked potentials (VEP) as input for a word processor (10-12 words/min), with an accuracy of 90%.

The Implanted BCI created by Kennedy et al [14] controls a cursor by measuring the rate of neural firing. Neural wave shapes are converted to pulses and the quantity of the pulses decides the action to follow, where the first and second pulses translate to moving up or down, right or left; and three pulses translates to a click on the computer mouse.

Scientists at the Ludwig Bolzmann Institute of Medical Informatics and Neuroinformattics, Graz, Austria developed theERS/ERD Cursor Control [15] This system reads the sensorimotor cortex and monitors event-related synchronization and desynchronization (ERS/ERD). The user has to control a cursor horizontally on the screen. (Accuracy 89-100% from 5 students and 60-51% from the other two).

Scientists from the Middendorf Scientific Services Inc., USA developed the Steady Visual Evoked Potentials(SVEP) BCI Flight simulator. Steady-state visual evoked potentials (SSVEPs) reflect power changes at the stimulus driving frequency and have been used to assess brain activity reflecting cognitive processing [16]. This BCI system uses Steady Visual Evoked Potentials and operant conditioning methods to train people to be able to control the direction of plane left or right. Scientists at the Laboratory of Nervous System Disorders, Wadsworth Center, New York State Department of Health and State University of New York, Albany 12201, USA developed the .Mu Rhythm Cursor Control. [17] The users can move the cursor up and down by imagined movement with an accuracy 90%.for vertical cursor control. Researchers at the Faculty of Science at the University of Technology Sydney, in Australia developed the Mind Switch Environmental Control Unit (ECU). This is activated by a burst in alpha brainwaves when a person closes their eyes ([18]. It is used to control a simple on/off switch, but can be easily adapted to operate a communication device. It has proved to be more than 90 per cent reliable in its latest trials with severely disabled people such as quadriplegics and stroke, polio or cancer-based sufferers [18]. The trials took place in the persons’ homes and participants used the ECU to control their television:

• switching on and off
• changing channels,
• altering the volume.

Most turned on the switch in one to three seconds more than 90 per cent of the time [18]. The above examples illustrate the potential of Brain Computer Interfaces but it is important that these devices are adaptable to the human wearing them. Our aim is to examine BCIs taking Social Weight Theory into account and is outlined in the next section.

4Social Weight Theory And BCIS

In order to be able to perform daily activities effectively, the BCI has to be a transparent device that allows the user to be action focused, with the freedom required to do this. The researchers contend that implementing wireless technologies with BCIs would help with the process of achieving such interface transparency. The BCI could start to be considered as an alternative input to the control devices on a daily basis. Ideally the BCI could be adapted to be a wearable computer and, as such, will need to address the issue of Social Weight [5]. As defined in Section 1, the Social Weight of an item of technology is defined to be the measure of the degradation of social interaction that occurs between the user and other people caused by the use of the item of technology. The components of Social weight are set out in the table below:

Component / Meaning
Cognitive load (CL) / Human processor resources required by the task
Physical Presence / Form factor, weight, fashion relevancy
Technology apprehension / Apprehension of other people
Social Weight / = g(CL + PP +TA)

Table 2: Components of Social Weight [19]

4.1Cognitive Load of a BCI

Thomas demonstrated the cognitive load of reading a display on various devices as measured against a model human processor and loss of eye contact [19]. Wearable devices such as Head Mounted Display Units have a high social weight as they may partially or totally occlude an eye. Reading from a PDA is classified as having a large Cognitive Load on the human processor and large loss of eye contact. By contrast, a wrist PC has a medium cognitive load on a human processor and involves only medium loss of eye contact. A pager monitor was classified as having a small/medium cognitive load on a human processor and no loss of eye contact. The BCI on the other hand could be considered as having a high cognitive load on a human processor but would score low on the loss of eye contact as the BCI is worn on the head and does not require loss of eye contact . However it is noted that with the Mind Switch[19 ] eye contact is lost as the switch is in fact operated by closing the eyes.

On the other hand the cognitive load on the human processor required by the task of a Brain Computer Interface has to be measured for every BCI system and application, as sometimes the use of this interface can vary considerably from one system to another. This will depend of the type of BCI utilized and the task that is being performed.For instance the cognitive load of the “Finger Switch“ by Mason and Birch [9] that uses low frequency bands and is driven by motor cortex recordings would score higher than the one by Sutter [13] that utilizes Steady Visual Evoked Potentials (SVEPs) where the user is not required to fully concentrate on the task, as the different frequencies in colour at which the user is staring are matched in the visual cortex.

4.2 Physical Presence of a BCIThe Form Factor

Form factor refers to the physical size and shape of the device – in this case the BCI. The difficulty in attaching the electrodes would add to its form factor. The physical presence of a BCI is also problematic –weight is low but its fashion relevancy would count against it.

Figure 3: Brain Computer Interface Cap

As shown it the photo above, wearers of a BCI cap immediately attract the attention of other people but not necessarily for the right reasons. BCI artifacts should be made to look good or in fashion. A person wearing a BCI would feel vulnerable as part of an excluded or socially rejected group. Given that many wearers of BCIs are already disabled the BCI could further damage their self esteem.

4.3Technology Apprehension of BCI

One of our authors participated in many sessions using a BCI whilst working at the Neil Squires Institute. The wearer of the BCI found it difficult to use and difficult place on her head. The BCI requires precision in positioning the electrodes in the exact location on the scalp. An assistant was required to put the necessary gel in each of the electrodes. The user finds this task a detriment to using a BCI as the process normally can take from thirty to forty minutes. A needle is used for application of the gel and the residue in the subject's hair after the BCI was removed was very distressing. There are also issues with having thick hair, as the gel in some cases doesn’t make contact with the scalp. Observers find the look of the typical BCI unappealing and some researchers have attempted to disguise the BCI as a baseball cap (see next section).

4.4Importance of Social Weight

As humans are inherently social it is important to design devices

• that people will actually use – if they feel inhibited they will limit their use of the device
• that do not limit how and when users access the device data {Thomas}.

In future research more precise results of the Social Weight of a Brain Computer Interface may be obtained by measuring a specific BCI system and application, as sometimes the use of this interface can vary considerably from one system to another. For instance, the social weight of using a BCI when navigating an aeroplane will score lower than the BCI system utilized to talk to somebody else [Spelling Device]. In the first case, the pilot is expected to use and be “seen“ with many types of devices to control and monitor the navigation of the plane, whereas in the second case you are not expected to be seen wearing a special device to talk or the device should not overwhelm the observers. For this reason Craig et al have developed the baseball cap BCI [19] for their BCI. As baseball caps are so common, people do not give wearers a second glance.

Figure 4: The New Mind Switch:

The Wearable Computer eSuit [5] also attempts to make the computing interfaces as unobtrusive as possible. The following devices are used as examples: a 2 line * 64 character watch display, a pager motor in a shoulder pad and LED lights on a suit cuff.

5Conclusion

The trajectory the BCI area has been continously limited, as shown in this paper, by technology constraints. Some of these constraints could be potentially solved by the use of interdisciplinary collaboration, advanced computer model techniques, improved hardware for online signal processing and communication tools. The convergence of digital and biological networks provides a more realistic platform for issues and potential problems to solve, for instance effective communication for the paralysed, breaking the frontiers of space and time, giving different forms of expression to humankind and effective learning techniques. This could lead to the futuristic conversion and transmission of information carried in bits and bytes to spikes for the stimulation of the corresponding neurons leading to a more effective human-to-human communication and interaction.